Europe's biggest bank by assets declined to say why it had increased litigation provisions to 2.4 billion euros, forcing it to correct its January 31 earnings report which already showed the worst quarterly loss in four years.

Sources familiar with the matter linked the higher provisions to recent developments in mortgage lawsuits targeting other banks that have made it more likely that Deutsche will have to pay plaintiffs to settle similar disputes and backdate the payments to 2012.

The bank said its proposed dividend would remain unchanged and reaffirmed an 8.5 percent target for its equity tier 1 capital ratio, a measure of its safety buffer for potential loan defaults, for the end of March.

Along with many of its peers, Deutsche faces a barrage of legal and regulatory challenges in the wake of the financial crisis.

In November, a U.S. judge rejected bids by Deutsche and Goldman Sachs Group Inc (GS.N) to dismiss a federal regulator's lawsuits accusing them of misleading Fannie Mae FNMA.OB and Freddie Mac FMCC.OB into buying billions of dollars of risky mortgage debt.

In August, Deutsche Bank and several other global banks came under investigation over business links to Iran, Sudan and other nations subject to U.S. economic sanctions.

Germany's financial regulator has said it would pass preliminary findings from a probe into suspected manipulation of interbank lending rates to the German finance ministry by the end of March.

Deutsche said last year's net income was 300 million euros, 400 million euros less than previously stated. The bank said full-year pretax income would fall to 800 million euros.